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It is generally accepted that El NiñoSouthern Oscillation (ENSO) is the main modulator of rainfall variability over Northern South America in the interannual scale. Assuming that, an index is proposed to quantify this expected interannual variability in time series of rainfall. The result is the exposure assessment to the effects of droughts, measured with the Standardized Precipitation Index (SPI) for the monthly scale. The SPI is calculated from rainfall series, and wavelet analysis is used to estimate the variance for different frequencies present in the signal. The Wavelet Interannual Variability Index (WIVI) is calculated as the sum of the wavelet coefficients over a predetermined range of modes of variability (with periods longer than 2 year and shorter than 8 years). The index was tested using a dataset of rainfall records from Tocantins state, Central Brazil. Most of the series ranged from 1974 to 2012. On average, the series had 3.2% of gaps which were not filled to avoid the effect of artificial trends on the data. The state lies mostly over the Cerrado biome and is a new frontier of agricultural development in Brazil. According to the results, the Northern region is under higher exposure of interannual variability, with higher values of WIVI. The assessment is in agreement with large‐scale features of South American climate, specifically considering the influences of the Pacific and Atlantic Oceans and their patterns of sea surface temperature (SST).

Climate change is expected to impact the hydrological regime worldwide, and land use and land cover change may alter the effects of the former in some cases. Secondary growth in deforested and abandoned areas is one of the main consequences of land use and cover changes in Amazonia. Among land uses, the effects of the secondary growth in water availability in large scale basins are not well understood. This work analyzes the potential effects of secondary growth under climate and land use change on water availability and hydropower in the Tocantins basin, in the Legal Amazon region of Brazil, using the MHD-INPE hydrological model driven by different climate scenarios and two future socioeconomic-based potential land use scenarios. The model projects decrease on discharge under climate change scenarios, which further cause the simulated hydropower energy potential to decrease significantly. When only deforestation scenarios are included, the effects of climate change are weakened, but when secondary growth is also considered, the effects of climate change are enhanced. Results suggest that different aspects of environmental change, such as secondary growth, may affect water production and the sectors depending on it.

We critically examined the performance of probabilistic streamflow forecasting inthe prediction of flood events in 19 subbasins of the Doce River in Brazil using theEta (4 members, 5 km spatial resolution) and European Centre for Medium-RangeWeather Forecasts (ECMWF; 51 members, 32 km resolution) weather forecastmodels as inputs for the MHD-INPE hydrological model. We observed that theshapes and orientations of subbasins influenced the predictability of floods due tothe orientation of rainfall events. Streamflow forecasts that use the ECMWF dataas input showed higher skill scores than those that used the Eta model for subbasinswith drainage areas larger than 20,000 km2. Since the skill scores were similar forboth models in smaller subbasins, we concluded that the grid size of the weathermodel could be important for smaller catchments, while the number of memberswas crucial for larger scales. We also evaluated the performance of probabilisticstreamflow forecasting for the severe flood event of late 2013 through a compari-son of observations and streamflow estimations derived from interpolated rainfallfields. In many cases, the mean of the ensemble outperformed the streamflow esti-mations from the interpolated rainfall because the spatial structure of a rainfallevent is better captured by weather forecast models.

This study assessed the impact of climate change on the hydrological regime of the Paraguaçu river basin, northeastern Brazil. Hydrological impact simulations were conducted using the Soil and Water Assessment Tool (SWAT) for 20202040. Precipitation and surface air temperature projections from two Regional Climate Models (Eta-HadGEM2-ES and Eta-MIROC5) based on IPCC5RCP 4.5 and 8.5 scenarios were used as inputs after first applying two bias correction methods (linear scalingLS and distribution mappingDM). The analysis of the impact of climate change on streamflow was done by comparing the maximum, average and reference (Q90) flows of the simulated and observed streamflow records. This study found that both methods were able to correct the climate projection bias, but the DM method showed larger distortion when applied to future scenarios. Climate projections from the Eta-HadGEM2-ES (LS) model showed significant reductions of mean monthly streamflow for all time periods under both RCP 4.5 and 8.5. The Eta-MIROC5 (LS) model showed a lower reduction of the simulated mean monthly streamflow under RCP 4.5 and a decrease of streamflow under RCP 8.5, similar to the Eta-HadGEM2-ES model results. The results of this study provide information for guiding future water resource management in the Paraguaçu River Basin and show that the bias correction algorithm also plays a significant role when assessing climate model estimates and their applicability to hydrological modelling.

Neotectonic activity was increasingly recorded over the Amazonian lowlands, even during historical times of a few tens of centuries. However, detailed analyses linking structures and styles of deformation are still few considering the large dimension of the region. Such events in a relatively recent time are expected to have caused conspicuous impacts on Amazonian ecosystems and forest disturbance. Changes in topography and hydrology by fracturing, faulting and folding during either subsidence or uplifting are direct effects on landscape that leave marks on the structure of the current forest, such as tree mortality and community succession. Two rectangular elbow-like shaped wetlands from the left margin of the middle Negro River valley in northwestern Amazonia were attributed to neotectonics. Remote sensing imagery was applied to test this hypothesis and also provide a tectonic model that can explain deformation dynamics in this area. The studied wetlands and adjacent river systems display various morphostructural anomalies compatible with a tectonic control, as well as lineaments paralleling main NW and NE-trending regional structures. The geomorphic analysis led to suggest that the wetlands are depressions formed by NW and NE-trending master boundary faults of horizontal displacements intercepted by various subsidiary faults. Transtensional strike slip regime is recorded by both left and right-lateral faults, with the wetlands corresponding to subsiding areas owned to conjugate strike slip faults. Habitat fragmentation and other ecological processes promoted by tectonic deformation would have impacted the overlying forest canopy by changing its structure due to tree mortality. The complex compartmentalization imposed by active tectonics would have exposed the ground to contrasting hydrological conditions, which controlled the rate of tree mortality within the wetlands. We pose that the tectonic disturbance and associated tree mortality documented in the middle Negro River evidence contemporary seismicity within the intracratonic Brazilian Amazonia.

We are obliged to several persons that enabled our research stay at ZF2. We thank Bruno Takeshi, Ana Paula Rocha, and Luciano Castilho for providing logistic support as well as all volunteer researchers who helped during the fieldwork and setup of the experiment. We thank Alacimar Guedes by the quality in the service of climbing the trees. Finally, we appreciate the helpful comments provided by the reviewers of this paper whose corrections have led to an improvement of the text. We thank the anonymous reviewers for their helpful suggestions and comments on the manuscript. The AmazonFACE program provided logistical support to conduct this study. The AmazonFACE program is funded by the Inter-American Development Bank through a technical cooperation agreement with the Brazilian Ministry of Science, Technology, Innovation and Communications (Grant BR-T1284); by Brazil’s Coordination for the Improvement of Higher Education Personnel (CAPES) Grant 23038.007722/2014-77; and by Amazonas Research Foundation (FAPEAM) Grant 2649/2014.

Sunscreen agents and in particular UV filters are compounds added in different cosmetic formulations, that has the function of preventing damage caused by sun exposition. Therefore, this paper proposes the development of a simple, fast and reliable electroanalytical method utilizing square wave voltammetry (SWV) to the determination of Benzophenone-3 (BZ-3), camphor 4-methylbenzylidene (MBC) and 2-ethylhexyl-4-methoxycinnamate (OMC) in cosmetic samples. The electrochemical system consisted of a cell with three electrodes: work – gold electrode modified, reference – Ag/AgCl(sat) and auxiliary – platinum, using as supporting electrolyte 4.0 mL of Britton Robinson Buffer 0.04 mol L-1 (pH=4.0), 1.0 mL of methanol and 5.50×10(-4) mol L-1 of cetyltrimethylammonium bromide (CTAB). The method was validated using three commercial sunscreen samples and the results showed recovery values between 83 and 98 %. The average values found for the analysed samples were 3.49 % m/m (728 mg L-1) to BZ-3, 0.56 % m/m (113 mg L-1) to MBC and 0.99 % m/m (208 mg L-1) to OMC. The detection (DL) and quantification (QL) limits were 0.47 mg L-1 and 1.56 mg L-1 to BZ-3, 0.77 mg L-1 and 2.58 mg L-1 to MBC and 0.78 mg L-1 and 2.59 mg L-1 to OMC, respectively. The sunscreen protector samples were also evaluated by high-performance liquid chromatography (HPLC) demonstrating a good correlation between the results and compared the results with allowed concentration.

Deforestation in the Amazon with its vast consequences for the ecosystem and climate is largely related to subsequent land use for cattle ranching. In addition to conservation policies, proposals to reduce deforestation include measures to intensify cattle ranching. However, the effects of land-use intensification on deforestation are debated in the literature. This paper introduces the abacra model, a stylized agent-based model to study the interplay of deforestation and the intensification of cattle ranching in the Brazilian Amazon. The model combines social learning and ecological processes with market dynamics. In the model, agents adopt either an extensive or semi-intensive strategy of cattle ranching based on the success of their neighbors. They earn their income by selling cattle on a stylized market. We present a comprehensive analysis of the model with statistical methods and find that it produces highly non-linear transient outcomes in dependence on key parameters like the rate of social interaction and elasticity of the cattle price. We show that under many environmental and economic conditions, intensification does not reduce deforestation rates and sometimes even has a detrimental effect on deforestation. Anti-deforestation policies incentivizing fast intensification can only lower deforestation rates under conditions in which the local cattle market saturates.

We provide a comprehensive analysis of the Holocene climate and vegetation changes over South America through numerical simulations. Holocene climate for several periods (8 ka, 6 ka, 4 ka, 2 ka, and present) were simulated by an atmospheric general circulation model, forced with orbital parameters, CO2 concentrations, and sea surface temperature (SST), while the analysis of the biome distributions was made with a potential vegetation model (PVM). Compared with the present climate, our four simulated periods of the Holocene were characterized by reduced South Atlantic Convergence Zone intensity and weaker South American Monsoon System (SAMS). The model simulated conditions drier than present over most of South America and gradual strengthening of SAMS toward the present. The Northeast Brazil was wetter because of southward migration of the intertropical convergence zone (ITCZ). Moreover, SST conditions were the main forcing for the climate changes during the mid Holocene inducing larger austral summer southward ITCZ migration. PVM paleovegetation projections are shown to be consistent with paleodata proxies which suggest fluctuations between biomes, despite the fact that ages of dry/wet indicators are not synchronous over large areas of the Amazonian ecosystem. Holocene PVM simulations show distinct retreat in Amazonian forest biome in all four simulated periods. In 6 ka, present caatinga vegetation in Northeastern Brazil was replaced with savanna or dense shrubland. The simulations also suggest the existence of rainforest in western Amazonia and the expansion of savanna and seasonal forest in the eastern Amazon, with shifts in plant community compositions and fragmentation located mostly in ecotone regions. Moreover, our PVM results show that during the Holocene, the Amazonian tropical forest was smaller in area than today, although western Amazonia persisted as a tropical forest throughout the Holocene.

Tropical secondary vegetation is of particular interest as carbon sinks, potential lands for agriculture and livestock expansion, biodiversity conservation and ecosystem services. Until mid-2000s estimates of secondary vegetation in the Brazilian Amazon indicated a progressive increase of this cover, however after 2010, only 1197 km 2 of additional secondary vegetation were generated, while 42,040 km 2 were converted into other land-covers. Meanwhile, deforestation rates progressively decreased to be around 6000 km 2 in contrast to the peak of 27,772 km 2 in 2004, what suggests that changes in land-cover dynamics with respect to deforestation may be related to a reduction in secondary vegetation. Hence, in this paper, we work with the hypothesis that, in a context of decreasing deforestation rates, the historic pattern of progressive accumulation of secondary vegetation in the Brazilian Amazon changed as a consequence of the re-conversion of this cover, as well as other land-covers relevant in the process of regeneration, into different land-covers that expanded in this period. Our focus was then to investigate, on a regional scale, the spatiotemporal patterns of secondary vegetation with respect to different land-covers in Pará based on (i) a quantitative analysis of transitions between land-covers, and (ii) on clustering patterns of secondary vegetation cover and their relations with clustering patterns of pastures, small-scale and industrial agriculture. We found that more secondary vegetation was converted into land-covers that expanded in the period i.e. clean pasture, mechanized agriculture, and palm oil, with secondary vegetation and land-covers important for regeneration (i.e. small-scale agriculture and regeneration with pasture) experiencing an overall reduction and contributing less to the concentration of secondary vegetation after 2010. Clusters of high values (hotspots) of secondary vegetation prevailed in the north, while clusters of low values (cold spots) prevailed in the south of Pará a pattern that is explained by different histories of occupation and deforestation dynamics, as well as distinct regional land dynamics in the past decade. As a first contribution to understanding the dynamics of secondary vegetation in a context of decreasing deforestation rates, our results show that the increased pressure to halt deforestation had effects over the dynamics of this land-cover, as well as over land-covers relevant to regeneration.

While food and nutrition security are issues that national and international organizations are tackling, one of the central problems often overlooked is the essential role of soils in providing nutritious food. Soils are the base for food production and food security. However, the majority of soils are in fair and poor conditions, with the most significant threats being erosion and loss of nutrients. In this study, we estimate the potential of soil loss, agricultural productivity loss, and nutrient loss for Brazils most important agricultural region, the Brazilian Cerrado, for the years 2000 and 2012. For this, we applied the Revised Universal Soil Loss Equation (RUSLE) model integrated with a geographical information system (GIS) to estimate annual soil loss rate and agricultural productivity loss, and used total nitrogen and total phosphorus in soil to estimate the annual nutrient loss rate caused by soil loss. All model factors and data were obtained from the literature. The results show that agricultural expansion in the Brazilian Cerrado is increasing the area of severe erosion, occasioning agricultural productivity decrease and soil nutrient depletion. The annual soil loss rate increased from 10.4 (2000) to 12.0 Mg ha−1 yr−1 (2012). Agricultural productivity loss occurred in more than 3 million hectares of crops and silviculture in 2000 and in more than 5.5 million hectares in 2012. Severely eroded areas lost between 13.1 and 25.9 times more nutrients than areas with low and moderate soil loss rates. These findings show that government policy should be directed to ensure the sustainable use of soils, mainly in agriculturally consolidated regions of the Brazilian Cerrado.

Resumo: A Mata Atlântica é um dos biomas brasileiros onde a partição das chuvas é mais estudada. No entanto, a maior parte das pesquisas é de curta duração, raramente ultrapassando um ano de coleta de dados. Investigações de longo prazo são importantes para avaliar a variação interanual desse processo hidrológico. O presente estudo teve como objetivo a quantificação da transprecipitação e a estimativa da interceptação das chuvas pelas copas das árvores na microbacia experimental B, recoberta com Floresta Ombrófila Densa Altomontana, no Laboratório de Hidrologia Florestal Walter Emmerich, Cunha-SP. Para esse propósito foi realizado o monitoramento da precipitação no aberto e da transprecipitação ao longo de três anos e 11 meses. Para a determinação da transprecipitação foram utilizados dez coletores (pluviômetros) de polietileno (galão e funil). Em uma parcela delimitada sob a floresta foram instalados trinta e seis suportes para acomodar os coletores. Semanalmente foram sorteados dez pontos diferentes onde eram instalados os coletores. A precipitação no aberto foi obtida por um dispositivo idêntico aos de transprecipitação e por três pluviógrafos localizados em área aberta da microbacia. A interceptação foi estimada pela diferença entre a precipitação no aberto e a transprecipitação média na parcela. Os resultados mostraram elevada variação interanual dos percentuais da transprecipitação e da interceptação em relação à precipitação no aberto, com valores variando entre 67% e 87% e 13% e 33%, respectivamente. Os percentuais de transprecipitação foram maiores no período chuvoso que no período pouco chuvoso, com valores médios de 78% e 68%, respectivamente. A interceptação, ao contrário, teve os maiores percentuais na estação pouco chuvosa (33%) que na chuvosa (22%). Regressões lineares simples correlacionando a transprecipitação e a precipitação no aberto apresentaram bom ajuste, com coeficiente de determinação superior a 91%, ao contrário das equações relacionando a interceptação com a precipitação no aberto, cujos coeficientes de determinação variaram de 9,2% a 66,1%.

ABSTRACT: The Atlantic Forest is one of the Brazilian biomes where the rainfall partitioning process is more studied. However, most research is short, rarely exceeding one year of data collection. Long-term research is needed to assess the interannual variation of this hydrological process. This study aimed to quantify the throughfall and interception of rain by canopy in the experimental catchment “B” covered with Dense Ombrophilous Forest, in the Walter Emmerich Forest Hydrological Laboratory, CunhaBrazil. For this purpose, monitoring of gross precipitation and throughfall over three years and 11 months was conducted. For the determination of the throughfall ten polyethylene containers were used in which plastic funnels were attached. In a plot delimited under the forest were installed thirty-six supports to accommodate the collectors. Ten different points were randomly drawn ten times by the generation of ten random numbers from 1 to 36 where the collectors were installed. The gross precipitation was obtained by a device similar to those of throughfall and the records of three tipping bucket rain gauges installed in clearing in the interior of the watershed. The interception was estimated by the difference between the gross precipitation and the mean throughfall in the plot. The results showed large annual variation in the percentage of throughfall and interception in relation to gross precipitation, with extreme values of 67% to 87% and 13% to 33% respectively. The percentage of throughfall were higher in the rainy season (October to March) that the little rainy season (April to September), with average values of 78% and 68%, respectively. The interception, by contrast, had the highest percentages in little rainy season (33%) than in the wet (22%). Simple linear regressions established between throughfall and gross precipitation in the annual open showed very good fit, with a coefficient of determination higher than 91%, unlike the equations relating the interception with gross precipitation, whose determination coefficients ranged from 9.2% to 66.1%.

RESUMEN: La Mata Atlántica es uno de los biomas brasileños donde la partición de las lluvias es más estudiada. Sin embargo, la mayoría de las investigaciones son de corta duración, rara vez superando un año de recolección de datos. Las investigaciones a largo plazo son importantes para evaluar la variación interanual de este proceso hidrológico. El presente estudio tuvo como objetivo la cuantificación de la precipitación de copas y la estimación de la interceptación de precipitación por las copas de los árboles en la microcuenca experimental B, recubierta con Bosque Ombrófilo Denso, en el Laboratorio de Hidrología Forestal Walter Emmerich, Cunha-Brasil. Para ese propósito se realizó el monitoreo de la precipitación bruta y de la precipitación de copas a lo largo de tres años y 11 meses. Para la determinación de la precipitación de copas se utilizaron diez contenedores de polietileno en los que se unieron embudos de plástico. En una parcela delimitada bajo el bosque se instalaron treinta y seis soportes para acomodar a los colectores. Diez puntos diferentes fueron dibujados al azar diez veces por la generación de diez números aleatorios del 1 al 36 donde se instalaron los colectores. La precipitación bruta fue obtenida por un dispositivo idéntico a los de precipitación de copas y los registros de tres pluviómetros de cubeta basculante instalados en claros en el interior de la cuenca. La intercepción se estimó por la diferencia entre la precipitación bruta y precipitación de copas media en la parcela. Los resultados mostraron gran variación interanual de los porcentajes de la precipitación de copas y de la interceptación en relación a la precipitación bruta, con valores extremos de 67% y 87% y 13% y 33%, respectivamente. Los porcentajes de precipitación de copas fueron mayores en el período lluvioso que en el período poco lluvioso, con valores medios de 78% y 68%, respectivamente. La interceptación, por el contrario, tuvo los mayores porcentuales en la estación poco lluviosa (33%) que en la lluviosa (22%). Las regresiones lineales simples correlacionando la precipitación de copas y la precipitación bruta presentaron muy buen ajuste, con coeficiente de determinación superior al 91%, al contrario de las ecuaciones relacionando la interceptación con la precipitación bruta, cuyos coeficientes de determinación variaron del 9,2% a 66 1%.

RESUME: La forêt atlantique est l’un des biomes brésiliens où la répartition des précipitations est plus étudiée. Cependant, la plupart des enquêtes sont de courte durée, dépassant rarement une année de collecte de données. Des études à long terme sont importantes pour évaluer la variation interannuelle de ce processus hydrologique. Cette étude visait à quantifier les pluviométrie au sol et une interception estimée de la cime des arbres de la pluie dans le bassin versant expérimental B, couvert de Forêt Tropicale Dense, le Laboratoire d’Hydrologie Forestière Walter Emmerich, Cunha-Brésil. A cet effet, a été suivi de la pluie incidente et pluviométrie au sol sur trois ans et 11 mois. La pluie incidente a été obtenue par la mesure dun pluviomètre et par lenregistrement de trois pluviomètres à auget basculeur installés dans des brèches à lintérieur du bassin versant. Pour la détermination du pluviométrie au sol, on a utilisé dix récipients en polyéthylène dans lesquels des entonnoirs en plastique étaient fixés. Sur une parcelle délimitée sous la forêt, trente-six supports ont été installés pour accueillir les collecteurs. Dix points différents ont été tirés au sort dix fois au hasard par la génération de dix nombres aléatoires de 1 à 36 où les collecteurs ont été installés. L’interception a été estimée par la différence entre La pluie incidente et le pluviométrie au sol dans la parcelle. Les résultats ont montré une grande variation annuelle du pourcentage de pluviométrie au sol et l’interception par rapport à la pluie incidente, avec des valeurs de 67% et 87% et 13% et 33%, respectivement. Les pourcentages étaient plus élevés dans des pluies période de bit pluviométrie au sol en saison des pluies avec des valeurs moyennes de 78% et 68%, respectivement. L’interception, en revanche, avaient les pourcentages les plus élevés en saison des pluies peu (33%) que dans l’humide (22%). La régression linéaire simple corrélation pluviométrie au sol et les pluie incidente a montré une très bonne forme, avec un coefficient de détermination dépassant 91%, à la différence des équations relatives à l’interception avec des pluie incidente, dont les coefficients de corrélation variaient de 9,2% à 66,1%.